1. Field of the Invention
The present invention relates to the technical field of mounted, trailed or self-propelled agricultural spreading appliances, and more particularly relates to agricultural spraying appliances. Such agricultural appliances are equipped with at least one boom intended to spread, as uniformly as possible, fertilizers or treatment products of the plant protection type on the ground or on crops. The relatively large dimensions of this boom mean that the mounted, trailed or self-propelled spreading appliance has to be of robust construction and appropriately suspended from the chassis.
Suspension devices advantageously allow the boom to move as the spreading appliance moves along over uneven ground. Furthermore, said suspension devices have to be capable of inclining the boom appropriately as the spreading appliance moves along over sloping terrain.
Pendular suspension devices for such booms are already known. These known suspension devices allow the boom to remain parallel to the ground as the chassis of the spreading appliance moves along over unevennesses of the ground. With such a suspension device, the boom is suspended from said chassis by a single articulation which therefore transmits to said boom the jolts which the chassis is experiencing.
There is also known a suspension device for a boom for spreading plant protection products which comprises elements for mounting said boom on a chassis to allow said boom to move with respect to said chassis.
2. Discussion of the Background
A suspension device of this kind is described, for example, in document FR 2 599 941-A1. This document specifically discloses a suspension device comprising two symmetric elements, each of which comprises:
a connecting rod connected, by one of its ends, so that it can pivot with respect to a fixed frame supported by a carrying machine, PA1 a cranked swinging arm, the top of which is mounted so that it can pivot with respect to the boom, while the end of its branch pointing toward the center is articulated to the second end of the connecting rod, and PA1 a tension spring, the ends of which are hooked respectively onto the connecting rod and onto the end of the second branch of the swinging arm facing outward.
A suspension device of this kind exhibits drawbacks. Specifically, it would seem that said suspension device incorporates no means for damping the movements of the boom. Furthermore, it would seem impossible to alter the geometry of the suspension device and thus the dynamic behavior of the boom.